This application claims priority from Japanese Patent Application 2001-374728, filed Dec. 7, 2001 which is incorporated herein by reference in its entirety.
1) Field of the Invention
The present invention relates to a vehicle headlamp in which optical axis adjustment is carried out smoothly. In the description, terms like back, front, vertical, and lateral indicate directions with respect to the vehicle.
2) Description of the Related Art
Vehicle headlamps having an optical axis adjustment mechanism have been described in, for example, Japanese Patent Applications Laid-Open Nos. H11-260115 and H11-329011.
The vehicle headlamps disclosed in these publications comprise a housing (1, 31) and a front lens (2, 32) forming a lamp chamber, a lamp bulb (5, 35A, 35B, 34, 52) housed in the lamp chamber, a reflector (3, 33, 31, 51) that reflects illumination light emitted from the lamp bulb (5, 35A, 35B, 34, 52) towards the front lens (2, 32) side, and an optical axis adjustment mechanism that supports the reflector (3, 33, 31, 51) on the housing (1, 31), so as to be able to adjust the optical axis.
The optical axis adjustment mechanism comprises, a ball joint (10, 40, 81, 82) that tiltably supports the reflector (3, 33, 31, 51) on the housing (1, 31), aiming screws (25, 26, 52, 53, 85, 86) rotatably supported on the housing (1, 31), and nut members (21, 22, 51, 52, 83, 84) mounted on screw portions of the aiming screws (25, 26, 52, 53, 85, 86), so as to be able to advance or retreat in the axial direction of the aiming screws (25, 26, 52, 53, 85, 86).
When the aiming screws (25, 26, 52, 53, 85, 86) are rotated, the nut members (21, 22, 51, 52, 83, 84) advance or retreat in the axial direction of the aiming screws (25, 26, 52, 53, 85, 86). Accompanying this, the reflector (3, 33, 31, 51) tilts vertically or laterally, about the ball joint (10, 40, 81, 82), with respect to the housing (1, 31). Thereby, the optical axis adjustment is carried out.
In the conventional vehicle headlamp, it is not possible to carry out the optical axis adjustment smoothly, so a vehicle headlamp in which it is possible to smoothly carry out the optical axis adjustment is in demand.
In the vehicle headlamp according to this invention, a transmission member is respectively connected swingably to a reflector and a nut member about an axis substantially orthogonal to the tilting direction of the reflector and to the advancing and backward direction of the nut member.
As a result, the transmission member provided between the reflector and the nut member forms a link in a link mechanism. Accordingly, the transmission member can convert a linear motion of the nut member to a rotation motion, and transmit the rotation motion to the reflector, and can also adjust a misalignment between the linear motion of the nut member and the rotation motion of the reflector. As a result, the optical axis adjustment can be carried out smoothly.
The reflector may be an integrated-type reflector in which a first reflector and a second reflector are provided integrally, and it is effective when a distance between a tilting fulcrum of the reflector (ball joint) and a transfer fulcrum of the nut member (a mounting point of the nut member and a screw portion of an aiming screw) is long, and an error between the linear motion of the nut member and the rotation motion of the reflector is large.
According to this invention, a front lens is a slant type front lens, in which the front lens largely inclines vertically or laterally, and the reflector is an integral type reflector in which the first reflector and the second reflector are provided integrally, in two stages back and front. It is further effective when the tilting fulcrum of the reflector and the transfer fulcrum of the nut member are not located on one plane orthogonal to the aiming screw, but shifted back and front, thereby the distance between the tilting fulcrum of the reflector and the transfer fulcrum of the nut member becomes long, and the error between the linear motion of the nut member and the rotation motion of the reflector is large.
These and other objects, features and advantages of the present invention are specifically set forth in or will become apparent from the following detailed descriptions of the invention when read in conjunction with the accompanying drawings.